During operation, Hard Disk Drives (“HDDs”) generate and create vibration as they rotate. By definition, a hard drive system will undergo rotational vibration when an oscillating moment is applied. When a hard disk drive is idle, the oscillation can be caused by friction in the spindle bearings or by rotational imbalance of the platter(s). When the drive is under “read/write” or “seek” conditions, inertia forces from activity of the actuator arm can cause rotational vibration (RV). This rotational vibration is characterized by “rad/s,” which is the rotational analog of linear acceleration m/s2 or g. When HDDs are packaged in close proximity, they can, and most often will, propagate RV from one drive to another, degrading drive performance. The vibration can become excessive, particularly when adjacent HDDs are operated simultaneously. Moreover, as HDD technology progresses to faster rotational speeds and cost-reduction architectures, the vibration problems are exacerbated.
In addition to the drive-to-drive induced vibration, there is also the above-discussed possibility of vibration being induced by the environment in which the drives are located. An example of this would be in a “data closet,” where network storage equipment is maintained; there could be a number of external sources that can induce vibration. An air conditioner in any relatively near location would be a good example.
Vibration can also come in the form of acoustic vibration; the HDDs can produce disturbing acoustic noise, particularly for the consumer product applications. As personal computers become more prevalent in the home and HDDs are being used for audio/video and entertainment applications, acoustic noise emissions are becoming important to consumers. Another factor in determining performance is acoustic noise by the HDD. For example, research has found that the leading question by consumers with respect to hard drives was, “How loud will this drive be in my system?” In analyzing the answer, the acoustic noise comes generally comes from two sources.
Excessive vibration may lead to decreased HDD performance such as recoverable and non-recoverable write inhibits, increased seek times, and increased read and write access times. Excessive vibration or shock may also cause premature HDD failures that are not repairable. Examples include mechanically-damaged platters and read/write heads, mechanical wear on moving HDD components, and data error defects that cannot be corrected through the use of software tools. Also if there are a large number of HDDs in a confined space, it may result in a substantial amount of heat generation. This heat must be dissipated in order to avoid overheating the HDDs and causing shortened product life.
Disk drives are complex electro-mechanical devices that can suffer performance degradation or failures due to a single event or a combination of events occurring over time. Environmental conditions that affect drive reliability include: ambient temperature, cooling air flow rate, voltage, duty cycle, shock/vibration, and relative humidity. Fortunately, it is possible to predict certain types of failures by measuring environmental conditions.
One of the worst enemies of hard disk drives is heat. Within a drive, the reliability of both the electronics and the mechanics (such as the spindle motor and actuator bearings) degrades as temperature rises. Running any disk drive at extreme temperatures for long periods of time is detrimental and can eventually lead to permanent data loss.
Currently, there is a void in the market as far as a “complete solution” that addresses vibration, thermal, and all other physical issues (mass, structure . . . ) for hard drives. The proliferation of hard drives is growing rapidly. One source estimates that the typical CAGR (compound annual growth rate) for the various segments of the Storage Area Network (SAN) and Network Attached Storage (NAS) arenas are growing at a .about.67% rate (typical). An increase in HDD performance will have a significant effect when considering the tremendous numbers of drives in operation. Much of the HDD industry continues to ignore the threat of damaging vibration as failure rates become exceedingly high. In some manner, the nature to solving many of these problems is the need to resolve “opposing constraints.” The constraints invariably pull many of the possible solutions in different directions. Almost without fail, all solutions find that in improving one problem constraint, they diminish the solution from the aspect of one, or more, of the other imposed constraints. The reality has become making trade-offs and finding a “balance” of the capabilities needed to satisfy the need(s).
In view of the foregoing disadvantages in the known types of HDD storage systems, the present invention provides a new solution wherein the same can be utilized for the storage of multiple hard drives or arrays of hard drives.